Production of lumber from raw logs typically involves a first step, called primary breakdown, of recovering an elongate square center from a log using head rig equipment. Head rigs generally comprise a large stationary circular saw or a band saw and a travelling carriage. The travelling carriage rotationally transports a log back and forth through the head rig to remove a series of rounded slabs from outer edges of the log thereby producing the squared center of the log which is commonly called a “cant”. In some processes, cants are produced with two squared-off opposing sides. Primary breakdown typically produces 2-sided and 4-sided cants, rounded edge slabs, and sometimes, large boards.
The cants, slabs and boards produced during primary breakdown are further processed during secondary breakdown processes whereby large rectangular side flitches having two opposing parallel sides, are cut from the sides of cants with band saws or circular saws. Flitches are then typically broken down into functional lumber with equipment having multiple parallel circular saw blades mounted onto a fixed driven arbor, commonly known as circular gang saws. The processing step for producing flitches from cants is known as “reducing” while production of functional lumber from flitches comprises multiple steps referred to as “edging” and “re-sawing”. High-volume through-put systems often combine the reducing and edging steps into one piece of equipment operating under high saw speeds to enable rapid cutting of wood against high pressures forced by rapid through-put of cants and flitches.
Pressing forces applied by high-volume throughput of flitches and lumber pieces against circular gang saws often cause undesired lateral movements and vibrations of individual saw blades resulting in deterioration in blade stability and reduced dimensional accuracy in the final finished lumber pieces. It is common practice to provide saw-guide assemblies comprising guidebars with or without babbitt pads interposed between individual blades to maintain their spacing and to minimize the extent of vibration that may occur. The sawguide assemblies are securely fixed into place between the individual circular blades by engagement with equipment frame rails or other support elements to provide stability to the saw blades prior to commencing operations. Some sawguide assemblies are provided with channels within the guidebars for flowing coolant therethrough to cool the individual circular saw blades. However, because of the extent of pressures exerted against the circular gang saws by cants and flitches, the spacing between the sawguides and saws may become skewed a few degrees on either side of the perpendicular plane relative to the arbor axis, thereby resulting in increased variability in the dimensions of the functional lumber pieces. Consequently, the operations have to be stopped so that sawguide assemblies can be partially disengaged from their mountings onto the equipment frame rails or supports, so their positioning can be adjusted to provide maximal contact and truing support to the individual sawblades. Such positioning and adjustments are often needed several times during a work shift resulting in reduced productivity and increased operating costs.